ブドウ‘巨峰’の結実と小花中の内生植物ホルモンとの関係

Abstract

The effects of dipping flower clusters before bloom in solutions of various plant growth regulators (GR) on the setting of parthenocarpic and seeded berries in 'Kyoho' grape were studied. The effects of a) dipping immature rachis in 2, 500 ppm succinic acid-2, 2-dimethyl hydrazide (SADH) and b) severe winter pruning on the content of endogenous plant growth substances in florets were also examined. The 'Kyoho' vines were trained to a vertical espalier and the pergola trellis systems.1. Dipping flower clusters in plant growth retardants, ((2-chloro-ethyl) trimethyl ammonium chloride) (CCC) and SADH significantly increased the set of seeded berries as compared to the control clusters. Among different dosages of GR, 2, 500 ppm SADH was most effective, independent of the training system; applications of growth promoters were ineffective in setting seeded berries. SADH also increased the number of seeds per berry, especially on vines trained to an espalier system.2. Severe pruning resulted in a high percentage set of seedless berries.3. An application of SADH decreased gibberellin (GA) and increased abscisic acid (ABA) contents in florets. Contrarily, severe pruning resulted in a rapid increase in GA level at bloom and a decrease in ABA content. The amount of cytokinins and indole-3-acetic acid (IAA) in florets also changed with these treatments. The amount of cytokinins increased with SADH treatment, but the relationship between the setting of seeded berries and the level of cytokinins and IAA in florets could not be established.These results suggest that poor berry setting in 'Kyoho' can not be explained by the theory of nutritional competition between cluster development and shoot growth. That endogenous plant growth substances, especially GA and ABA, in the florets are closely associated with the setting of seeded berries became evident in this study.